{ INFORMATICS.MCCME.RU
  Problem statement: http://informatics.mccme.ru/moodle/mod/statements/view3.php?chapterid=317
  Verdict: Accepted
}
uses SysUtils, Math;
 
var
	n,k:int64;
 
function fact(a:int64):int64;
var 
	i:longint;
begin
result:=1;
for i:=2 to a do
	result:=result*i;
end;
 
begin
reset(input,'input.txt');
rewrite(output,'output.txt');
read(n,k);
write(fact(n) div (fact(k)*fact(n-k)));
end.